Update multimedia/libdvdread and multimedia/libdvdnav

• Update multimedia/libdvdread to version 5.0.1
• Update multimedia/libdvdnav to version 5.0.2
• Bump revisions of ports that depend on multimedia/libdvdnav (library version is going backwards from 4.2.1 to 4.1.2)
• Ports depending on multimedia/libdvdread do not need to be bumped (the library keeps being numbered 4.1.2 and is binary compatible with the previous version)